Accumulating evidence suggests that prostaglandins may play important regulatory roles in various aspects of mammalian reproduction. Little is known, however, of the possible function of these potent biologic substances in the reproductive activity of avian species. In view of the ubiquity of prostaglandins in nature and the global significance of the domestic fowl as a major source of animal protein, this research proposal is designed to establish and clarify the role of prostaglandins in the reproductive physiology of the domestic hen. The studies will be conducted both in vitro and in vivo. By means of sensitive radioimmunoassay, the occurrence and distribution of prostaglandins in blood and reproductive organs will be determined at various stages of the egg cycle. Inhibitors of prostaglandin synthesis and specific antisera will be used to elucidate whether prostaglandins are essential in the process of ovulation and oviposition (egg laying). These studies will be correlated with measurements of the steroid and pituitary hormone background of the laying hen, particularly as they relate to the endocrine events that have been implicated in the initiation of ovulation and oviposition. Physiological and biochemical studies including the interaction of prostaglandins, oxytocin, adrenergic mechanisms, and cyclic nucleotides (cAMP and cGMP) in situ and on isolated segments of the reproductive tract will be carried out and integrated into the proposed research.